Rough running, sooty plugs


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spdtrpl
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Rough running, sooty plugs

Post by spdtrpl »



Hello,
I bought a 2005 GL1800 with 48,000 miles on it two weeks ago, it would not idle and would only run roughly above 2000 rpms. I believe the bike had been sat for some time so I replaced the gas and added a large volume of seafoam and she would then idle badly but would run slightly roughly throughout the range.. Plugs were very black and sooty

I ran a compression test which was excellent, spark looks good on all cylinders, checked the valves which are all good, put in a new air filter, new plugs which are gapped correctly, replaced the gas with seafoam mix with new fresh gas, there are no FI errors. I ran the bike at idle until hot without touching the throttle which I read resets the ecu.

I just pulled the fuel injectors and had them tested and apparently they are good, I thought I had a fuel pressure problem so I installed a new fuel pump and a new fuel pressure regulator. I checked the fuel pressure at approx 45 psi to 50 psi. I believe the vacuum hose is ok as I get a variation in fuel pressure when I close off the vacuum hose to the fuel pressure regulator.

Just took her for a run and she’s still misfiring and (new) plugs are again very sooty and black. Exhaust temps are the same on all 6 cylinders so I don’t see it as a coil/ignition wire problem.
would a blocked or faulty ICV cause these problems? Any thoughts about the rich running condition and culprits?
Does anyone have any ideas what to look for next?

thanks for any help
Mike


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Re: Rough running, sooty plugs

Post by WingAdmin »

I'd look at the oxygen sensor next. A failed/failing oxygen sensor can definitely cause the engine to run rich.
Techdude2000
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Re: Rough running, sooty plugs

Post by Techdude2000 »

spdtrpl wrote: Sun Aug 04, 2024 2:48 pm Hello,
I bought a 2005 GL1800 with 48,000 miles on it two weeks ago, it would not idle and would only run roughly above 2000 rpms. I believe the bike had been sat for some time so I replaced the gas and added a large volume of seafoam and she would then idle badly but would run slightly roughly throughout the range.. Plugs were very black and sooty

I ran a compression test which was excellent, spark looks good on all cylinders, checked the valves which are all good, put in a new air filter, new plugs which are gapped correctly, replaced the gas with seafoam mix with new fresh gas, there are no FI errors. I ran the bike at idle until hot without touching the throttle which I read resets the ecu.

I just pulled the fuel injectors and had them tested and apparently they are good, I thought I had a fuel pressure problem so I installed a new fuel pump and a new fuel pressure regulator. I checked the fuel pressure at approx 45 psi to 50 psi. I believe the vacuum hose is ok as I get a variation in fuel pressure when I close off the vacuum hose to the fuel pressure regulator.

Just took her for a run and she’s still misfiring and (new) plugs are again very sooty and black. Exhaust temps are the same on all 6 cylinders so I don’t see it as a coil/ignition wire problem.
would a blocked or faulty ICV cause these problems? Any thoughts about the rich running condition and culprits?
Does anyone have any ideas what to look for next?

thanks for any help
Mike
Have you checked the FI system voltage while it’s running? Bad connections that can develop in C5, a blue junction connector can cause it to run poorly as it robs the system of power. The black/yellow wires at the ECM connectors should read very close to battery voltage while the key is on. If it reads low, C5 is your culprit. If your power checks ok, you could have a bad baro sensor. It can go bad and not throw a code, but have the mixture too rich for your elevation.
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Re: Rough running, sooty plugs

Post by spdtrpl »

Techdude2000 wrote: Tue Aug 06, 2024 6:40 pm
spdtrpl wrote: Sun Aug 04, 2024 2:48 pm Hello,
I bought a 2005 GL1800 with 48,000 miles on it two weeks ago, it would not idle and would only run roughly above 2000 rpms. I believe the bike had been sat for some time so I replaced the gas and added a large volume of seafoam and she would then idle badly but would run slightly roughly throughout the range.. Plugs were very black and sooty

I ran a compression test which was excellent, spark looks good on all cylinders, checked the valves which are all good, put in a new air filter, new plugs which are gapped correctly, replaced the gas with seafoam mix with new fresh gas, there are no FI errors. I ran the bike at idle until hot without touching the throttle which I read resets the ecu.

I just pulled the fuel injectors and had them tested and apparently they are good, I thought I had a fuel pressure problem so I installed a new fuel pump and a new fuel pressure regulator. I checked the fuel pressure at approx 45 psi to 50 psi. I believe the vacuum hose is ok as I get a variation in fuel pressure when I close off the vacuum hose to the fuel pressure regulator.

Just took her for a run and she’s still misfiring and (new) plugs are again very sooty and black. Exhaust temps are the same on all 6 cylinders so I don’t see it as a coil/ignition wire problem.
would a blocked or faulty ICV cause these problems? Any thoughts about the rich running condition and culprits?
Does anyone have any ideas what to look for next?

thanks for any help
Mike
Have you checked the FI system voltage while it’s running? Bad connections that can develop in C5, a blue junction connector can cause it to run poorly as it robs the system of power. The black/yellow wires at the ECM connectors should read very close to battery voltage while the key is on. If it reads low, C5 is your culprit. If your power checks ok, you could have a bad baro sensor. It can go bad and not throw a code, but have the mixture too rich for your elevation.



Thanks for the suggestion,

Just replaced all the plug leads but sadly the misfire remains.

As you suggested I tried checking the supply voltage to the ECM - On the Grey connector there appear to be two black yellow wires one measures 12.90v versus the 13.2v on my battery which seems reasonable. But the yellow/black connected to I believe B2 shows 0v.
Doesn't seem correct but I'd appreciate your opinion.


Additionally I tried to test the output of the pulse generator I believe it should be 0.7v but I measure it at 0.27v. As I do not have the official honda voltmeter perhaps this low value is due to the sampling or impedance of my multimeter?



Thanks again for the help
Techdude2000
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Re: Rough running, sooty plugs

Post by Techdude2000 »

spdtrpl wrote: Fri Aug 09, 2024 3:11 pm
Techdude2000 wrote: Tue Aug 06, 2024 6:40 pm
spdtrpl wrote: Sun Aug 04, 2024 2:48 pm Hello,
I bought a 2005 GL1800 with 48,000 miles on it two weeks ago, it would not idle and would only run roughly above 2000 rpms. I believe the bike had been sat for some time so I replaced the gas and added a large volume of seafoam and she would then idle badly but would run slightly roughly throughout the range.. Plugs were very black and sooty

I ran a compression test which was excellent, spark looks good on all cylinders, checked the valves which are all good, put in a new air filter, new plugs which are gapped correctly, replaced the gas with seafoam mix with new fresh gas, there are no FI errors. I ran the bike at idle until hot without touching the throttle which I read resets the ecu.

I just pulled the fuel injectors and had them tested and apparently they are good, I thought I had a fuel pressure problem so I installed a new fuel pump and a new fuel pressure regulator. I checked the fuel pressure at approx 45 psi to 50 psi. I believe the vacuum hose is ok as I get a variation in fuel pressure when I close off the vacuum hose to the fuel pressure regulator.

Just took her for a run and she’s still misfiring and (new) plugs are again very sooty and black. Exhaust temps are the same on all 6 cylinders so I don’t see it as a coil/ignition wire problem.
would a blocked or faulty ICV cause these problems? Any thoughts about the rich running condition and culprits?
Does anyone have any ideas what to look for next?

thanks for any help
Mike
Have you checked the FI system voltage while it’s running? Bad connections that can develop in C5, a blue junction connector can cause it to run poorly as it robs the system of power. The black/yellow wires at the ECM connectors should read very close to battery voltage while the key is on. If it reads low, C5 is your culprit. If your power checks ok, you could have a bad baro sensor. It can go bad and not throw a code, but have the mixture too rich for your elevation.



Thanks for the suggestion,

Just replaced all the plug leads but sadly the misfire remains.

As you suggested I tried checking the supply voltage to the ECM - On the Grey connector there appear to be two black yellow wires one measures 12.90v versus the 13.2v on my battery which seems reasonable. But the yellow/black connected to I believe B2 shows 0v.
Doesn't seem correct but I'd appreciate your opinion.


Additionally I tried to test the output of the pulse generator I believe it should be 0.7v but I measure it at 0.27v. As I do not have the official honda voltmeter perhaps this low value is due to the sampling or impedance of my multimeter?



Thanks again for the help
Ok, you have to have a peak voltage adaptor to measure the pulse from the CKP. Was your power readings at the ECM taken with it running?
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Re: Rough running, sooty plugs

Post by spdtrpl »

My multimeter has a peak hold feature, but if the pulses are of short duration I can see why it wouldn't accurately measure it.
I took the power measurements with the ECU disconnected and the ignition switched on. I didn't think of taking them with the motor on as I assumed they were direct from the battery, probably a mistake - Should I redo them with the motor running?
I don't have a breakout box so I'll have to find a way to probe into the wire.
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Re: Rough running, sooty plugs

Post by Techdude2000 »

spdtrpl wrote: Fri Aug 09, 2024 5:44 pm My multimeter has a peak hold feature, but if the pulses are of short duration I can see why it wouldn't accurately measure it.
I took the power measurements with the ECU disconnected and the ignition switched on. I didn't think of taking them with the motor on as I assumed they were direct from the battery, probably a mistake - Should I redo them with the motor running?
I don't have a breakout box so I'll have to find a way to probe into the wire.
Yes, your meter will still try to average the voltage and it occurs at the same rate as 6 times the engine rpm. You should back probe them with the ECM plugged in and the engine running. The issue with the junction connector is a bad connection develops and it starts melting the connector and letting the pins move around. This will cause a voltage drop only when loaded by the FI system. This is a common issue with the 01-08 models. Honda used a much better connector for this circuit in the later model years. There was a 2008 a few years ago that had their baro sensor go bad. It wasn’t bad enough to go out of its normal range, so it wouldn’t throw a code, but it was causing the mixture to be really rich at the altitude of the bike.
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Re: Rough running, sooty plugs

Post by Asphaltmaniac »

An air leak will have the ECU addding more fuel.
Last edited by Asphaltmaniac on Wed Aug 14, 2024 10:58 am, edited 1 time in total.
spdtrpl
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Re: Rough running, sooty plugs

Post by spdtrpl »

Asphaltmaniac wrote: Wed Aug 14, 2024 10:46 am Have you had the shelter off? Did the last owner do their own service?
Yes shelter has been off a couple of times and is currently off while I’m faultfinding.
I don’t know the service history of this bike, but when I bought it I found a new air filter, new’ish plug leads, so some work had been done. Whether it was done correctly is another question.
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Re: Rough running, sooty plugs

Post by spdtrpl »

Current situation:
Bike misfires both at idle and at all higher revs
Plugs will get very black and sooty even after running for a few minutes.

Valves checked
New air filter
New plugs
ECU reset many many times
New fuel in tank
Tank has been cleaned
New fuel pump
Fuel injectors tested, cleaned and tested again
New fuel regulator
New spark plug leads
New ignition pulse generator
Just tried another ECU
Spark plugs leads are going to the correct plugs
Coil input leads are going to the correct coils
Fuel injector connections are going to the correct fuel injectors.
Battery is new and shows 14.2v (lithium)
Ait and map are receiving 5v
TPS getting battery voltage
And after all these changes still have the misfire.
I have tried unplugging the map/air temp and baro sensors while running to see if that changes the situation but it doesn’t.
C5 connector looks like new as do the other multi pin connectors by the relay bank that I can’t remember the names of.

Any new ideas as to what could be causing the ultra rich condition?


Thanks again
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Re: Rough running, sooty plugs

Post by Rambozo »

Have you checked the oxygen sensors?
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Re: Rough running, sooty plugs

Post by spdtrpl »

No I haven’t. Not sure how to but thanks for the suggestion. I’ll test them next.
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Re: Rough running, sooty plugs

Post by spdtrpl »

I wonder if the TPS could be bad and it’s telling the ECU that the throttle is wide open and so causing the rich condition?

However I don’t get any codes.

Thoughts??
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Re: Rough running, sooty plugs

Post by Asphaltmaniac »

All plugs sooty so it affecting both sides. If it were an 02 sensor only one side would be affected and im sure there would be an F1 light. I think you might have an airleak. if it were me and the shelter was off Id remove the snorkels and while it running place both hands over the intakes and see what happens. Also under the airbox are these two rubber gasket type things.


Maybe if the bike sat for awhile the meeces found them tasty???
I'm wondering is there a difference in the plug sootyness from one side to the other?
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Re: Rough running, sooty plugs

Post by Rambozo »

If it's rich enough to make the plugs black, it should be throwing codes.
You can measure the output from the O2 sensors with them hooked up and running. The voltage will be in the ballpark of the CO percentage. .7 volts is about right. If it reads 1 volt then it is telling the ECU it is way rich and should set a code. I have seen some older fuel additives ruin O2 sensors by coating them with a film that clogs the pores.
If you unplug the O2 sensors it will run in open loop and be at least close to running ok. If you have access to a Lambda scope you can track the O2 vs injector duty cycle and see if it is even trying to go into closed loop.
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Re: Rough running, sooty plugs

Post by GoldWingrGreg »

There is an inner harness ground crimp towards the left side on the IAT sensor. It's in the harness with the IAT wires. Usually within about 6" or 9" from where the wires come out. Be sure to wiggle that area of the harness to see if there is any change in it poor running.
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Re: Rough running, sooty plugs

Post by Techdude2000 »

Did you check the Baro Sensor’s signal line to see if it’s stuck high or low?
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Re: Rough running, sooty plugs

Post by spdtrpl »

Techdude2000 wrote: Fri Aug 16, 2024 11:00 am Did you check the Baro Sensor’s signal line to see if it’s stuck high or low?
I haven’t done that. I just tried unplugging the sensor to see if has any effect and it didn’t…is that a good enough test or should I measure the voltages?
Having now done a bunch of things I need to write it all down as I reckon I must be missing something. When I’ve done that list I’ll publish it and appreciate your feedback.

Thanks again
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Re: Rough running, sooty plugs

Post by spdtrpl »

Rambozo wrote: Wed Aug 14, 2024 7:19 pm If it's rich enough to make the plugs black, it should be throwing codes.
You can measure the output from the O2 sensors with them hooked up and running. The voltage will be in the ballpark of the CO percentage. .7 volts is about right. If it reads 1 volt then it is telling the ECU it is way rich and should set a code. I have seen some older fuel additives ruin O2 sensors by coating them with a film that clogs the pores.
If you unplug the O2 sensors it will run in open loop and be at least close to running ok. If you have access to a Lambda scope you can track the O2 vs injector duty cycle and see if it is even trying to go into closed loop.
JustrRan the bike with the O2 sensors unplugged and unfortunately still misfired.
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Re: Rough running, sooty plugs

Post by Techdude2000 »

spdtrpl wrote: Fri Aug 16, 2024 11:37 am
Techdude2000 wrote: Fri Aug 16, 2024 11:00 am Did you check the Baro Sensor’s signal line to see if it’s stuck high or low?
I haven’t done that. I just tried unplugging the sensor to see if has any effect and it didn’t…is that a good enough test or should I measure the voltages?
Having now done a bunch of things I need to write it all down as I reckon I must be missing something. When I’ve done that list I’ll publish it and appreciate your feedback.

Thanks again
If it’s stuck high, it would be the same as unplugging it. I would check the actual signal level with it plugged in and running.


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